Resolve “X is not a verified user” When Adding Developer to Facebook App Roles

Whilst recently building my first Facebook app, one of the things I wanted to do was share ownership with another developer so we could both work on it and share other apps in the future. When trying to add this other user I kept getting an error returned claiming that they were not a verified user.

When looking into how to resolve this I saw a number of possible causes mentioned across the web, from the app being in ‘Sandbox’ mode, to groups not being setup correctly.

None of these proposed solutions worked and after digging a little further I found this page on Facebook help:

It turns out that to be added to a role for a Facebook app you need to verify your account via phone or by adding a credit card. After trying the steps explained on the page above I was then able to add the second developer successfully.